1. Field of the Invention
This invention relates to a method of regenerating an alcohol-based antifreezing liquid and, more specifically, to a method of regenerating an alcohol-based antifreezing liquid diluted through water absorption by concentrating the liquid through removal of water therefrom.
2. Prior Art
Various kinds of alcohol-based antifreezing liquids have been known which include, for example, ethanol and other alcohols, and mixtures of alcohol and other liquids, such as propylene glycol. Such alcohol-based antifreezing liquid is generally utilized in freezing foodstuffs, and for this purpose the so-called liquid immersion method is often used. This method is such that foodstuffs are immersed for a given period of time in an alcohol-based antifreezing liquid which has been stored and cooled in a tank open on the top side, being then removed.
In the liquid immersion method, the antifreezing liquid is cooled to several tens of degree below zero centigrade or even to a temperature near -100.degree. C., and in such condition the surface of the antifreezing liquid is in contact with air. Therefore, moisture in the water is absorbed through the liquid surface into the liquid and the antifreezing liquid is thus diluted. When a low-temperature antifreezing liquid is diluted with water, some poor condition of agitation develops and this results in a liquid temperature rise. In order to prevent such temperature rise, a usual practice has been to discharge the antifreezing liquid in part from the tank periodically and add a fresh supply of antifreezing liquid (of high concentration). However, the trouble is that such practice involves high running cost and does not pay. Moreover, such practice poses a problem from the standpoint of waste treatment or disposal.